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Discussion Starter #1 (Edited)
Another question regarding my basement bathroom build. The vanity we want won't fit in the spot where the current drain is so I want to move it over about 5 feet to the right of where the stack is in the picture below. I'm concerned with distance from the stack, it will be about 6 feet after it's all done. It's a 1 1/2"" stack, the main stack is on the other side of the house. The drain already there is sloped, so I was hoping to just be able to put a coupling on that end then continue the drain to where it needs to be, between the 3rd and 4th stud to the right.

 

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You wll be more than 5 feet away from the vent---so that new drain opening will need a vent---vent pipe must be above the height if the sink---
 
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Discussion Starter #3 (Edited)
You wll be more than 5 feet away from the vent---so that new drain opening will need a vent---vent pipe must be above the height if the sink---
Ok, I was thinking something like the drawing below then, would it work? Does the vent have to be sloped? The only other thing hooked up to this drain stack is the upstairs washing machine.

 

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Check the elevation on your horizontal line. It should be about 19" for a lavatory, possibly lower depending on the sink and whether it's a drop in or undermount, and the height of the cabinet.

The picture you show will work fine. You are allowed 90* on a trap arm. Further than that requires a cleanout.


Vent should be flat or slope back toward the fixture it serves. I often find it easier to run them with 1/8" per foot grade than it is to make them perfectly flat.
 

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Discussion Starter #5
The pic I posted is something I found on Google, just wanted to display how I was going to run the vent and if that would be acceptable.

I just measured and the current drain is about 15" high. We plan on installing a vanity with a drop in sink, so I think we should have enough height based on that. Haven't decided on the specific vanity yet but will have a look around this weekend to get an idea of working heights on the drains and what not.
 

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NPC allows for 6 feet total length on an 1 1/2" trap arm and a total change of direction of 135 degrees or a 90 + a 45.
So as long as you can keep it under 6 feet between the tee and the p-trap connection you should be fine (assuming you come in between 16-19" off the floor.

If you can't make 6 feet, you could either do what your picture shows, or you could replace that 2x2x1 1/2 tee with a 2" tee and run that trap arm in 2" pipe. A 2" trap arm allows for an 8 foot run instead of 6, just 90 out at the centre of your fixture and put a 2x1 1/2" reducing MJ coupling to bring it down to 1 1/2" for your p-trap connection.

Code also calls for the vents to slope towards the drain to allow any condensate or rain water in the venting system to drain out instead of sitting around cutting down airflow or choking it out completely.
 

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Discussion Starter #7 (Edited)
Well I just went and double checked that stack. I assumed it was a 2" stack but it turns out that it's a 1 1/2" stack and the drain coming off is also a 1 1/2".

Is the code for running a 1 1/2" drain 5 feet or 6 feet? If it's 6 feet then I might be ok. 5 feet than I might have to run that extra vent.
 

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Are you sure it's 1 1/2"? From your picture it appears as if the stack is run in 2" and the trap arm is 1 1/2". Never the less, to paraphrase the code, the total length in feet of a TRAP ARM is 4x the pipe diameter.
1 1/4" or 1.25 x4 = 5 Feet
1 1/2" or 1.5 x4 = 6 Feet
2" x4 = 8 Feet etc... etc... etc...
 

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Discussion Starter #9
It's definitely a 1 1/2" stack all the way around, I just went down and checked because I too thought it would have been a 2" stack.
 
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